Initial backing-up of certificates.

Suggested by #12
and #9

extern.h

@@ -184,7 +184,7 @@ int		 chngproc(int, const char *, int);
 int		 dnsproc(int);
 int		 revokeproc(int, const char *, 
 			int, int, const char *const *, size_t);
-int		 fileproc(int, const char *);
+int		 fileproc(int, int, const char *);
 int		 keyproc(int, const char *,
 			const char **, size_t, int);
 int		 netproc(int, int, int, int, int, int, int, int, int,

fileproc.c

@@ -21,9 +21,11 @@
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <unistd.h>
 
 #include "extern.h"
@@ -64,13 +66,15 @@ serialise(const char *tmp, const char *real,
 }
 
 int
-fileproc(int certsock, const char *certdir)
+fileproc(int certsock, int backup, const char *certdir)
 {
 	char		*csr, *ch;
 	size_t		 chsz, csz;
 	int		 rc;
 	long		 lval;
 	enum fileop	 op;
+	time_t		 t;
+	char		 file[PATH_MAX];
 
 	csr = ch = NULL;
 	rc = 0;
@@ -99,6 +103,45 @@ fileproc(int certsock, const char *certdir)
 		warnx("unknown operation from certproc");
 		goto out;
 	} 
+
+	/*
+	 * If we're backing up, then copy all files (found) by linking
+	 * them to the file followed by the epoch in seconds.
+	 * If we're going to remove, the unlink(2) will cause the
+	 * original to go away.
+	 * If we're going to update, the rename(2) will replace the
+	 * certificate, leaving the backup as the only one.
+	 */
+
+	if (backup) {
+		t = time(NULL);
+		snprintf(file, sizeof(file),
+			"cert-%llu.pem", (unsigned long long)t);
+		if (-1 == link(CERT_PEM, file) && ENOENT != errno) {
+			warnx("%s/%s", certdir, CERT_PEM);
+			goto out;
+		} else
+			dodbg("%s/%s: linked to %s", 
+				certdir, CERT_PEM, file);
+
+		snprintf(file, sizeof(file),
+			"chain-%llu.pem", (unsigned long long)t);
+		if (-1 == link(CHAIN_PEM, file) && ENOENT != errno) {
+			warnx("%s/%s", certdir, CHAIN_PEM);
+			goto out;
+		} else
+			dodbg("%s/%s: linked to %s", 
+				certdir, CHAIN_PEM, file);
+
+		snprintf(file, sizeof(file),
+			"fullchain-%llu.pem", (unsigned long long)t);
+		if (-1 == link(FCHAIN_PEM, file) && ENOENT != errno) {
+			warnx("%s/%s", certdir, FCHAIN_PEM);
+			goto out;
+		} else
+			dodbg("%s/%s: linked to %s", 
+				certdir, FCHAIN_PEM, file);
+	}
 
 	/* 
 	 * If revoking certificates, just unlink the files. 

main.c

@@ -81,19 +81,22 @@ main(int argc, char *argv[])
 			  rvk_fds[2];
 	pid_t		  pids[COMP__MAX];
 	int		  c, rc, newacct, remote, revoke, force,
-			  staging, multidir, newkey;
+			  staging, multidir, newkey, backup;
 	extern int	  verbose;
 	extern enum comp  proccomp;
 	size_t		  i, altsz, ne;
 	const char	**alts;
 
 	alts = NULL;
 	newacct = remote = revoke = verbose = force = 
-		multidir = staging = newkey = 0;
+		multidir = staging = newkey = backup = 0;
 	certdir = keyfile = acctkey = chngdir = NULL;
 
-	while (-1 != (c = getopt(argc, argv, "FmnNrstvf:c:C:k:"))) 
+	while (-1 != (c = getopt(argc, argv, "bFmnNrstvf:c:C:k:"))) 
 		switch (c) {
+		case ('b'):
+			backup = 1;
+			break;
 		case ('c'):
 			free(certdir);
 			if (NULL == (certdir = strdup(optarg)))
@@ -383,7 +386,7 @@ main(int argc, char *argv[])
 		free(alts);
 		close(dns_fds[0]);
 		close(rvk_fds[0]);
-		c = fileproc(file_fds[1], certdir);
+		c = fileproc(file_fds[1], backup, certdir);
 		/*
 		 * This is different from the other processes in that it
 		 * can return 2 if the certificates were updated.